administration today. what can you tell us about them? >> well, scott, nusra is one of a number of shadowy radical islamist groups on the ground. they've been welcomed by many syrians because of their numerous military successes. but the arrival of these types of groups has created a real shift on the ground that we as journalist cans even feel. rebel fighters now asking us "do you work for the c.i.a.? do you work for israel?" a lot more talk about jihad. and often these voices are drowning out the voices of more moderate activists. >> pelley: anything can happen in this volatile part of the world. clarissa, thanks very much. egypt remains divided too. thousands protests tonight both for and against president mohammed morsi. some tried to scale the walls of the presidential palace. morsi is insisting on a national vote this saturday on a new constitution, but opponents say it takes away too many of their rights. a killer is caught on video just before he pulled the trigger. how sand saved some homes from s